This invention relates to a connector, such as a direct type lamp socket, adapted to connect a lamp tube and to a backlight assembly using the connector.
Recently, a large-sized liquid crystal display is widely used in various technical fields. A backlight module used in the large-sized liquid crystal display comprises a small-diameter lamp tube, such as CCFL (cold cathode fluorescent lamp) and EEFL (external electrode fluorescent lamp), as a light source. A system in which a liquid crystal glass is irradiated directly by a light from the lamp tube located behind the liquid crystal glass is called a direct type. The direct-type system is excellent in light utilization efficiency and is most suitable for a backlight of a liquid crystal display, such as a monitor and a television, requiring a high brightness.
For a conventional direct-type backlight module, several systems are known.
In a first system, a backlight module comprises a metal casing called a chassis and a plurality of lamp tubes arranged on one surface of the chassis and spaced from one another. Each lamp tube has lead wires as electrode portions at opposite ends thereof. The lead wires are connected to one ends of cables by soldering, respectively. One end of each electrode portion connected to each cable by soldering is coated with a rubber member. The cable extracted from the rubber member has the other end to which a terminal is crimped. The terminal is received in a connector housing and is connected to a connector mounted to an inverter substrate disposed on the other surface of the chassis. Thus, the lamp tube is supplied with electric power through the connector and the cable.
In another system, a connector comprising an insulator, a terminal portion, and a slider member is mounted to an inverter substrate. The connector extends through a chassis to a lamp tube mount surface. An electrode portion of a lamp tube is directly connected to the terminal of the connector. In this system, after the lamp tube is incorporated into the terminal portion of the connector, the slider member is operated to connect a lead wire of the lamp tube and a contact. After the lead wire and the contact are connected to each other, the lead wire is relatively firmly fixed.
However, in the system in which the lamp tube is supplied with electric power through the cable, the lamp tube is connected to the inverter substrate through the rubber member, the cable, and the connector. Therefore, a large number of components are used and a large number of operation steps is required. Further, upon exchanging a fluorescent tube, other components must be exchanged together. This brings about an increase in cost. In addition, the lamp tube with the cable soldered thereto is easily broken during handling.
In the system in which the connector is mounted onto the inverter substrate and the lamp tube is directly connected thereto, it is possible to achieve reduction in number of components and easy attachment/detachment of the lamp tube. However, various kinds of stresses are caused to occur, for example, a stress generated during contact due to a positioning error at assembling of the lamp tube and the connector, a stress of vibration or mechanical shock applied during transportation or during use of a liquid crystal assembly, or a stress due to heat shrinkage of the lamp tube resulting from heat generation of the lamp tube itself. These stresses concentrate to the lead wire of the lamp tube or a lead wire sealing portion and may result in breakage of the lamp tube or a shortened lifetime of the lamp tube.
A socket for connecting a typical lamp is disclosed, for example, in Japanese Unexamined Patent Application Publication (JP-A) No. 2003-257570. A socket for connecting a fluorescent tube is disclosed, for example, in Japanese Unexamined Patent Application Publication (JP-A) No. 2002-367422. However, the techniques disclosed in these publications can not solve the above-mentioned problems.
A backlight assembly and a lamp holder are disclosed in, for example, Japanese Unexamined Patent Application Publication (JP-A) No. 2002-367422 and Japanese Unexamined Patent Application Publication (JP-A) No. 2003-257570, respectively. However, these techniques are disadvantageous in that a large number of components and a high cost are required.